Influence of forest harvesting activities on debris avalanches and flows

Erosion processes in steep terrain—Truths, myths, and uncertainties related to forest management in Southeast Asia

“…The major effect of conversion of forest land to agriculture on landslide erosion can be attributed to a more or less permanent loss in rooting strength compared to previous forest or brush vegetation (Sidle et al, 1985;Sidle, 2005). Shallowrooted agronomic species and grasses have negligible rooting strength compared to deeper-rooted trees and shrubs (Rice et al, 1969;Marden and Rowan, 1993;Bergin et al, 1995).…”

“…The effects of agroforestry practices on landslide erosion are much the same as for forest conversion to agriculturei.e., decreased rooting strength and the occasional incorporation of terraces (that are subject to failure) in steep terrain increase the probability of landslides (Sidle, 2005). However, depending on the density of tree plantings in agroforesty systems, rooting strength of the site may be higher than in strictly cropland or pasture conditions, albeit less then typical rooting strength of mature forests (Fig.…”

Enhanced sediment delivery in a changing climate in semi-arid mountain basins: Implications for water resource management and aquatic habitat in the northern Rocky Mountains

“…Forest roads are widely recognized to increase sediment supplied to forest streams by altering hillslope hydrology and sediment flux (Megahan, 1974;Reid and Dunne, 1984;Ziegler and Giambelluca, 1997;Luce and Black, 1999;Croke and Mockler, 2001;MacDonald et al, 2001;Wemple et al, 2001;Arnáez et al, 2004), thereby reducing water quality and aquatic habitat suitability . The combined effect of low infiltration capacity of road surfaces (Luce and Cundy, 1994) and interception of surface flow and throughflow by cutslopes (Wemple and Jones, 2003) is increased surface runoff (Luce, 2002), leading to frequent erosion from the road surface (many events per year) and periodic mass failures from the adjacent hillslopes (Montgomery, 1994;Ziegler et al, 2004;Sidle, 2005). Improvement and removal of forest roads is another approach available to land managers to effectively reduce sediment inputs (Luce, 1997;Madej, 2001;Switalski et al, 2004).…”

Integrating uncertainty: Canyon Creek hyperconcentrated flows of November 1989 and 1990

“…Debris avalanches and debris flows initiating from oversteepened road fill slopes, and redirected drainage concentrating on steep slopes are a common legacy of past forestry operations in the Pacific Northwest (e.g., Megahan and Kidd 1972;Swanston and Swanson 1976;Montgomery 1994;Jakob 2000;Sidle 2005;Rollerson et al 2005). Within clearcuts, debris avalanches typically occur 7 to 15 years after logging because of the loss of root cohesion and associated shear strength in the surrounding soils (O'Loughlin 1974;Wu et al 1979).…”